Card Ninja From Uchiha - Chapter 4

Chapter 4: The Weight of Potential

Yami stared at his reflection in the small bathroom mirror, his dark eyes studying the young face that looked back at him. Five years old. A child by any measure, with soft features that hadn’t yet hardened into the sharp Uchiha look. But behind those eyes was a mind that understood something most people in this world took for granted.

Chakra wasn’t just energy. It was the fusion of two fundamental forces—physical energy drawn from the body’s cells, and spiritual energy cultivated through training and experience.

The Uchiha clan was blessed with exceptional spiritual energy. It was why their Sharingan was so powerful, why they excelled at genjutsu, why their Yin affinity tended to run high. Generations of selective breeding and natural talent had made spiritual strength a clan trademark.

But that blessing came with a hidden curse.

High spiritual energy meant the Uchiha naturally had strong Yin chakra. But their Yang chakra—their physical energy, their vitality, their bodily strength—tended to lag behind. Not dramatically, not enough to cripple them, but enough to create an imbalance.

Yami had seen it in the cards floating above clan members’ heads. Yin affinity at Level 2 or 3 was common among the Uchiha. Yang affinity at Level 1 was almost universal.

And he was no different. His Yin affinity was now Level 5, enhanced by extracting Shisui’s card. His Yang affinity remained stubbornly at Level 1.

That imbalance meant his chakra growth would be lopsided. His spiritual energy would develop quickly, but without sufficient physical energy to balance it, his total chakra capacity would remain limited.

The solution was obvious: he needed to train his body. Build physical strength, improve his vitality, force his Yang energy to grow through hard work and exercise.

Which is why, on the morning of his second week in this world, Yami stood in the small open space of his apartment and prepared to begin the most ridiculous training regimen he could think of.

The Saitama routine.

100 push-ups.

100 squats.

100 sit-ups.

10KM of running.

In his previous life, it had been a joke—the training method of a fictional character who became absurdly powerful through simple exercise. The humor came from its mundane nature, the idea that basic calisthenics could somehow lead to godlike strength.

But Yami wasn’t looking for godlike strength. Not yet, anyway. He was looking for any improvement at all, any way to stimulate his body’s growth and increase his physical energy. And if nothing else, this routine was comprehensive and didn’t require equipment he didn’t have.

The fact that he was five years old and this routine was designed for adults didn’t escape him. It was probably too much. Possibly dangerous. Definitely going to hurt.

But what choice did he have?

Yami got down on the floor and positioned himself for the first push-up.

His arms trembled as he lowered himself. His body weight, light as it was, felt like an enormous burden. He managed three push-ups before his arms gave out and he collapsed onto his face.

Three. Ninety-seven to go.

He rested for a moment, then forced himself back up. Two more push-ups. Rest. Three more. Rest. His arms burned, his shoulders ached, sweat dripped from his forehead despite the morning coolness.

It took him nearly an hour to complete one hundred push-ups, broken into sets so small they barely qualified as sets. By the end, his arms were useless noodles, shaking uncontrollably whenever he tried to lift them.

The squats were marginally easier—his legs were stronger than his arms—but still brutal. His thighs screamed in protest, his knees felt unstable, and by rep seventy he was seriously questioning whether this was going to permanently damage his developing body.

But he pushed through. One hundred squats, completed in forty minutes of pure suffering.

Sit-ups were perhaps the worst. His core muscles, underdeveloped and unprepared, cramped and spasmed. He had to stop multiple times to let the cramps pass, massaging his stomach and trying not to cry from the pain.

One hundred sit-ups. Done.

He lay on the floor afterward, staring at the ceiling, wondering if he had just made a terrible mistake. His entire body felt like it had been beaten with hammers. Everything hurt—muscles he didn’t even know he had were screaming in agony.

And he still had to run ten kilometers.

Yami forced himself to his feet, swaying slightly. His legs didn’t want to support his weight. His vision swam for a moment before clearing.

Come on. You can do this. You have to do this.

He changed into slightly looser clothes, drank some water, and headed out of his apartment with determination that was ninety percent stubbornness and ten percent actual willpower.

The Uchiha compound had several training grounds, ranging from advanced facilities for practicing ninjutsu to simple open fields for running and basic conditioning. Yami headed for one of the latter, a track that circled a large field where clan members sometimes held taijutsu sparring sessions.

He started running.

His pace was slow, more of a jog than anything impressive. His breathing became labored within minutes. His legs, already exhausted from the squats, protested every step.

But he kept going. Lap after lap around the track, his small feet slapping against the packed earth. Other clan members were present, some training seriously, others just going through morning exercises. A few glanced at him with curiosity—a five-year-old child running laps with such determination was unusual—but most ignored him.

Yami lost count of the laps. Distance became meaningless. Time blurred. All that existed was the next step, then the next, then the next.

When he finally collapsed, unable to take another step, he had no idea if he’d actually completed ten kilometers or not. It felt like he’d run a marathon. His lungs burned, his legs were numb, and dark spots danced at the edges of his vision.

A clan member jogging by—a middle-aged woman with concern in her eyes—stopped to check on him.

“Are you alright, child?” she asked, crouching beside him.

Yami managed a nod, too exhausted to speak.

“Don’t push yourself too hard,” she advised gently. “You’re still very young. Training is important, but so is letting your body recover.”

He nodded again, and she helped him to his feet before continuing her own workout.

Yami limped back to his apartment, barely able to climb the stairs. Once inside, he collapsed onto his futon and closed his eyes, trying to ignore the full-body ache that had settled into his bones.

After several minutes of lying there in misery, he summoned the energy to enter his Card Dimension and check his status.

—

Health: 22/30

Chakra: 15/15

…

Ninja: Lv3 (0/10)

Bloodline: Sharingan Lv5 (0/100,00,000)

Ability: CARD (LvMax), Kotoamatsukami Lv1(0%), Susanoo Lv1(0%), Insight Lv1(0%), Genjutsu Lv1(0%)

Affinity: Fire (Lv3), Yin (Lv5), Yang (Lv1)

Jutsu: Clone Lv1 (0%)

Skills: Chakra Control Lv3 (0%)

—

Nothing had changed. Not a single point of experience gained. His Ninja Level was still at 3, requiring 10 experience to reach Level 4. His chakra remained at 15.

All that suffering, all that effort, and he had gained absolutely nothing.

Yami felt despair creep into his chest. If this was how it was going to be—brutal training with no results—then what was the point? How was he supposed to survive in this world if he couldn’t even increase his basic stats?

He exited the Card Dimension and lay on his futon, staring at the ceiling through tear-blurred eyes. His body hurt, his spirit felt crushed, and for the first time since arriving in this world, he seriously questioned whether he could actually do this.

—

The next three days were hell.

Yami could barely move. Every muscle in his body screamed in protest at the slightest movement. Getting out of bed required careful planning and considerable willpower. Walking to the bathroom felt like climbing a mountain.

Hana, his neighbor, knocked on his door on the second day, bringing him some soup she’d made.

“I heard you were training hard at the compound,” she said, her expression a mix of concern and approval. “That’s good, but you need to be careful. You’re still very young, and pushing too hard can cause injuries that never fully heal.”

Yami thanked her for the soup and assured her he would be more careful. The truth was, he didn’t know if he’d be able to continue the training at all. The pain was so severe, the results so nonexistent, that the whole endeavor felt pointless.

But on the fourth day, when the worst of the soreness had faded to a dull ache, Yami forced himself to think analytically about the problem.

Why hadn’t he gained any experience from training?

The answer came to him slowly, piecing together what he knew about this world and the card system.

Yang affinity determined how quickly you could improve your physical capabilities through training. Level 1 Yang affinity—which is what he had—meant his body’s ability to grow stronger through exercise was severely limited. Not impossible, but slow. Painfully slow.

Maybe so slow that a few hundred push-ups wouldn’t register as significant progress. Maybe he needed weeks or months of consistent training before his body adapted enough to show measurable improvement.

Or maybe there was another way.

If the problem was his low Yang affinity, then the solution was to increase it. And he could increase it the same way he’d increased his Yin and Fire affinities—by extracting a higher-level Yang affinity card from someone else.

The plan was simple. Go out into Konoha, find someone with higher Yang affinity than his own, extract their card, and merge it with his. Boost his Yang affinity to Level 2 or higher, and suddenly his training would become effective.

Simple in concept. Difficult in execution.

Because Yang affinity, it turned out, was remarkably rare.

—

Yami spent an entire day wandering through the Uchiha compound and the adjacent Konoha districts, his extraction sense active but his Sharingan concealed. He looked at hundreds of people, examining the cards floating above their heads.

What he found was illuminating and frustrating in equal measure.

Most civilians had either no Yang affinity card at all, or no Yin affinity card. Sometimes they lacked both. These were people who were medically unfit to become ninja, whose bodies or minds simply couldn’t handle the rigors of chakra manipulation and combat.

Those without Yang affinity couldn’t build physical strength through training. No matter how much they exercised, their bodies wouldn’t respond with significant improvement. They could maintain basic fitness, but true physical power—the kind ninja possessed—would always be beyond their reach.

Those without Yin affinity were rarer, and for good reason. Yin chakra was tied to mental and spiritual energy. Having no Yin affinity meant severe mental instability or disability. Most people without it never lived to adulthood, or if they did, they required constant care.

Some people had low Yin affinity instead of none at all. Might Guy and Rock Lee were examples Yami knew from the series—individuals who struggled to learn ninjutsu and genjutsu, whose spiritual energy was so limited that they could barely mold chakra for anything beyond basic techniques. They compensated by focusing entirely on taijutsu, building their bodies to incredible heights to overcome their lack of versatility.

But Yang affinity at Level 2 or higher? That was rare even among active ninja.

Yami checked every Uchiha clan member he passed. Almost universally, they had Level 1 Yang affinity. The clan’s focus on developing their Sharingan and genjutsu had, over generations, created a population with strong spiritual energy but mediocre physical energy.

He needed to find someone with Uzumaki or Senju blood—lineages known for their exceptional Yang chakra. But the options were limited and mostly inaccessible.

Naruto Uzumaki was a newborn, host to the Nine-Tails, and almost certainly under ANBU protection somewhere in the village. Finding him would be impossible for a five-year-old with no resources or connections.

Karin Uzumaki was probably a baby somewhere in Kusagakure, far beyond Yami’s reach.

Tsunade Senju had left Konoha after the deaths of her brother and lover, wandering the world as a gambler and medical ninja. She wouldn’t return to the village for years.

Obito Uchiha had Hashirama’s cells implanted in his body, giving him exceptional Yang chakra. But he was also a missing-nin, the man behind the Nine-Tails attack, and possessed the Kamui ability that made him nearly impossible to track or corner.

As for Danzo… Yami wasn’t sure if the old war hawk had already implanted Hashirama’s cells into his body or not. The timeline was fuzzy on when exactly that happened. And even if Danzo did have them, getting close enough to extract a card from him would be suicidal.

All the best sources of high-level Yang affinity were either unavailable, too dangerous, or too well-protected.

Yami felt frustration building as he wandered through Konoha’s streets, checking person after person and finding nothing useful. The sun was setting, painting the sky in oranges and reds, and he still hadn’t found a single person with Yang affinity above Level 1.

He was beginning to think this approach was doomed to failure when he realized something.

He didn’t need to find someone with Level 5 Yang affinity. He just needed Level 2. Even a small improvement would make a difference in his training efficiency.

And if he couldn’t find anyone with Level 2 Yang affinity today, well, he could keep looking. Eventually, he’d encounter someone—a visiting ninja from another village, a retired jonin, someone with Senju blood in their lineage.

The key was patience and persistence.

—

Yami returned to his apartment as darkness fell, exhausted from walking all day but feeling slightly more optimistic. He had a plan, even if it would take time to execute.

And in the meantime, he could still train. Even if the results came slowly, they would come eventually.

He decided to try again, but more carefully this time. Instead of pushing himself to the absolute limit, he would do what his body could handle and slowly build up capacity.

He started with squats. Not one hundred—just twenty-five, performed with proper form and controlled breathing.

When he finished, he entered his Card Dimension to check his status.

The Ninja Level card still showed (0/10).

No change.

Disappointed, he tried push-ups. Twenty-five again, the most he could manage with his still-recovering arms.

He checked the card again.

Ninja: Lv3 (1/10)

Yami stared at the number, hardly believing it. One point of experience. Just one, but it was there. His training had finally registered as progress.

The difference between today and four days ago suddenly made sense. Four days ago, he’d done the training in one intense burst, probably injuring his muscles in the process. His body had been overwhelmed, unable to process the stimulus as growth because it was too much damage all at once.

But today, after days of rest and recovery, his body was ready to adapt. The exercise was difficult but manageable, pushing him without breaking him. And that made all the difference.

Encouraged, Yami moved on to sit-ups. Another twenty-five, performed carefully.

Ninja: Lv3 (2/10)

Another point of experience.

Finally, even though it was dark outside, he went down to the training ground and ran. Not ten kilometers—he wasn’t ready for that yet. Maybe three or four, jogging at a comfortable pace that elevated his heart rate without leaving him gasping.

When he returned home and checked his status, it showed (3/10).

Three points of experience in one evening. At this rate, if he trained every day, he could level up his Ninja level in just over three days.

But as he examined the card more closely, new information appeared—details he hadn’t noticed before.

—

Ninja Level Progression:

Lv1 to Lv20 → Academy Student

Lv21 to Lv40 → Genin

Lv41 to Lv60 → Chunin

Lv61 to Lv80 → Jonin

Lv81 to Lv100 → Kage

Lv101 to Lv120 → Bijuu (Zero-Tails)

Lv121 to Lv140 → Bijuu (One-Tail)

…

—

The progression chart continued upward, with each Bijuu level representing increasingly massive amounts of chakra and power. Yami couldn’t see the full extent of the chart—it seemed to go higher than the interface would display—but the implications were clear.

He was currently Level 3. An Academy Student ranged from Level 1 to 20. He wouldn’t be considered a true ninja—not even a genin—until he reached Level 21.

That meant he had 18 levels to gain before he could even think of himself as a legitimate shinobi. And each level would require 10 experience points, meaning 180 total experience points.

If he gained 3 experience per day through training, that would take 60 days. Two months.

But that was assuming he maintained this training every single day, never missed a session, and his body continued to respond at this rate. It also assumed his Yang affinity stayed at Level 1. If he could boost it to Level 2, his training efficiency would increase dramatically.

Yami lay on his futon, his body pleasantly tired rather than agonizingly painful, and felt something that had been absent for days.

Hope.

Not the desperate, grasping hope of someone drowning, but the steady, grounded hope of someone who could see a path forward. It would be long. It would be hard. There would be setbacks and challenges.

But it was possible.

He could grow stronger. Could increase his chakra. Could eventually learn jutsu and become a real ninja capable of surviving the dangers this world would throw at him.

The Mangekyō Sharingan had given him incredible abilities—extraction, storage, and now Kotoamatsukami. But those abilities were useless without the chakra to fuel them. A sword was worthless if you lacked the strength to swing it.

So he would train. Every day, consistently, patiently building his foundation. He would search for someone with higher Yang affinity and extract their card when the opportunity arose. He would practice the techniques he had collected, bringing them from Level 1 understanding to genuine mastery.

And slowly, painfully, one hard-earned experience point at a time, he would transform from a helpless five-year-old child into a ninja worthy of the name.

The road ahead was long.

But Yami had already died once. He’d been given a second chance in a world he thought was fictional.

He wasn’t going to waste it.

Tomorrow, he would train again. And the day after that, and the day after that.

However long it took, whatever sacrifices were required, he would survive.

And maybe, just maybe, he would become strong enough to change the tragedies he knew were coming.

The Uchiha massacre. The Fourth Shinobi War. The Otsutsuki invasion.

They were years away still, distant threats that seemed almost abstract from his current perspective.

But they were real. They would happen. Unless someone changed the future.

Yami closed his eyes, feeling sleep pull him down into darkness.

One step at a time, he thought. Get stronger first. Worry about saving the world later.

In the quiet apartment, in the recovering village, a five-year-old boy carrying the memories of two lives dreamed of a future where he was strong enough to protect the people who mattered.

And in the morning, he would take another step toward making that dream reality.